Novel Insights into Inkjet Printed Silver Nanowires Flexible Transparent Conductive Films

Silver nanowire (AgNWs) inks for inkjet printing were prepared and the effects of the solvent system, wetting agent, AgNWs suspension on the viscosity, surface tension, contact angle between ink droplet and poly(ethylene) terephthalate (PET) surface, and pH value of AgNWs ink were discussed. Further, AgNWs flexible transparent conductive films were fabricated by using inkjet printing process on the PET substrate, and the effects of the number printing layer, heat treatment temperature, drop frequency, and number of nozzle on the microstructures and photoelectric properties of AgNWs films were investigated in detail. The experimental results demonstrated that the 14-layer AgNWs printed film heated at 60 °C and 70 °C had an average sheet resistance of 13 Ω∙sq⁻¹ and 23 Ω∙sq⁻¹ and average transparency of 81.9% and 83.1%, respectively, and displayed good photoelectric performance when the inkjet printing parameters were set to the voltage of 20 V, number of nozzles of 16, drop frequency of 7000 Hz, droplet spacing of 15 μm, PET substrate temperatures of 40 °C and nozzles of 35 °C during printing, and heat treatment at 60 °C for 20 min. The accumulation and overflow of AgNWs at the edges of the linear pattern were observed, which resulted in a decrease in printing accuracy. We successfully printed the heart-shaped pattern and then demonstrated that it could work well. This showed that the well-defined pattern with good photoelectric properties can be obtained by using an inkjet printing process with silver nanowires ink as inkjet material.     

Printability of functional inks on multilayer curtain coated paper

Printability of functional inks on multilayer curtain coated substrates was investigated. The inks represent those commonly used to produce solution processable electronic devices, such as organic transistors. The substrate, which combines sufficient barrier and printability properties for printed functional devices, was manufactured utilizing high speed curtain coating technique. The coating structure consists of a mineral pigment layer coated on top of a barrier layer. The combination of the two layers allows for controlling the absorption of ink solvents. By adjusting the thickness, porosity and surface energy of the top-coating the printability can be tuned for various functional inks. Focus was set on printing conducting silver and carbon inks, both with nano- and micrometer sized particles, as well as printing of an organic semiconductor, poly(3-hexylthiophene). The pore volume in the top-coating determined the spreading of the micrometer sized silver ink as well as the amount semiconductor per area required, whereas the pore size was the determining factor regarding penetration of the nano-sized silver ink. As a proof of concept hygroscopic insulator field effect transistors were printed on the multi-layer curtain coated paper using a custom-built roll to roll hybrid printer.     

Optimizing inkjet printing process to fabricate thick ceramic coatings

This article describes the use of Taguchi optimization and ANOVA techniques on inkjet printing process to determine optimal parameters for fabrication of thick ceramic coatings over glass substrates. Stable nanoparticle suspensions are synthesized through high energy milling of precursor powders with adequate quantities of binder and suspending solvent. Most often, inkjet printing process is being used for developing fine and thin layers (<10 µm). However, an attempt is made to fabricate thick ceramic films by varying only IJP process parameters and without multiple layer deposition, thereby reducing efforts in ink synthesis and processing time of coated substrates. Three parameters of IJP were varied for developing a model that was used for precisely predicting the printed layer thickness under varying process parameters. ANOVA technique showed that open time interval in combination with nano particle concentration in the ink could potentially lead to thick coatings. The higher volume % of solvent in the diluted suspension ink under the influence of substrate heating contributed significantly to coffee stain effect with irregular surface coatings. However, increasing the concentration of nanoparticles in the diluted ink resulted in substantial improvement in thickness of the layer with simultaneous control of coating defects.     

Roll-to-roll gravure printing of thick-film silver electrode micropatterns for flexible printed circuit board

This paper presents a novel method for printing thick silver electrodes with high fidelity using a rotogravure technique and high-viscosity silver ink. The widths and thicknesses of the printed electrodes were investigated with respect to the printing angle and printing speed. In addition, the use of a low-surface-energy polyethylene terephthalate substrate was found to decrease the ink transfer for printing angles of up to 60°, possibly because of the small adhesive force at the interface between the ink and substrate. We therefore employed substrates with higher surface energies, namely polyimide and treated polyimide, to enhance the ink transfer. A lower printing speed of 0.5 m/min and high viscosity of 15 Pa·s are required to obtain better functionality with a lower resistivity. However, using the proposed method, the fidelities of the printed patterns were achieved even with a high printing speed of 10.5 m/min using the high viscosity of 15 Pa·s, necessitating a subsequent sintering process. Therefore, the printed pattern was sintered in an oven at 350°C for 10 min. Patterned silver electrodes 1 m in length, 121 ± 2.2 μm in line width, 6.5 ± 2.2 μm in average thickness, and with a resultant resistivity of 9 µΩ·cm were achieved. The findings of this study confirm the potential of rotogravure printing for fabricating thick electrodes with high fidelity for flexible printed circuit boards with large areas.     

新型水溶性油墨清洗剂的研制及其应用

文章研制出一种新型油墨清洗剂,具有安全、高效、低成本的特点,能克服直接使用溶剂带来的易燃、易爆等缺点.此新型油墨清洗剂是由表面活性剂、乳化剂、溶剂及其它助剂构成的O/W型微乳液.研究结果表明,此油墨清洗剂各组分的复配比对其使用性能具有较大影响,此清洗剂可替传统溶剂型油墨清洗剂用于印刷机件上油墨的清洗,且安全、高效.在清洗温度不低于25℃的条件下,水与清洗剂的稀释比为3∶1,对油墨的去除率达到100％.     

印刷油墨清洗剂的研究及开发进展

印刷油墨清洗剂是印刷行业用来清除印刷油墨的一种精细化学品。文章对传统的汽油、煤油类印刷油墨清洗剂及混合溶剂型,乳液、微乳液型,水基、半水基型,天然成分环保型等新型印刷油墨清洗剂的研究及开发进展进行了综述;概括分析可知传统汽油、煤油类印刷油墨清洗剂,对环境、工作人员的健康有严重的影响,环境友好、安全性高且质优价低是新型油墨清洗剂的研制目标。     

Direct Printing of Thermal Management Device Using Low‐Cost Composite Ink

This work presents a new method for fabricating thermal devices, such as heat sinks, using a 3D printing technique and lightweight composite ink. The method focuses on formulating composite inks with desired properties and direct ink writing for manufacturing. The ink undergoes two phases: phase one uses low viscosity epoxy to provide viscoelastic properties and phase two provides the fillers consisting of carbon fiber and graphite nanoplatelets to provide high thermal conductivity and structural properties. By combining these functional materials, 3D structures with a high thermal conductivity (≈2 W m⁻¹ K⁻¹) are printed for thermal management applications with the storage modulus of 3000 MPa and a density only 1.24 g cm⁻³. The results show that by carefully tailoring functional properties of the ink, net‐shape multifunctional structures can be directly printed for thermal management device applications, such as heat sinks.     

3D printing of shape memory poly(d,l-lactide-co-trimethylene carbonate) by direct ink writing for shape-changing structures

Four-dimensional (4D) printing of shape memory materials has attracted increasing interests for personalized structures. In this study, a biocompatible poly(d ,l -lactide-co-trimethylene carbonate) (PLMC) is utilized to fabricate 4D shape-changing structures with customized geometries through direct ink writing. The printed objects show shape transformations at different dimensions under thermal programming. The influence of the printing parameters on the properties including rheological, solvent evaporation, and static mechanical behavior are systematically investigated. A printing map is further depicted to achieve high-quality printing with high viscous ink flowed from micronozzle to construct various structures. The printed structures in one-dimensional, two-dimensional, and three-dimensional (3D) exhibit shape-changing behavior with fast response around body temperature. The fast responsive time shows potential in the field of surgical suture (4 s), nonwoven fabric (3 s), and self-expandable stent (35 s). The feasibility of 3D printing of PLMC opens the way for applications in shape-changing devices with small diameter. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48177.     

基于3D打印技术制造柔性传感器研究进展

与传统的涂覆、沉积等加工手段相比,使用3D打印技术可制造复杂立体功能结构的传感器,将3D打印与柔性传感技术结合可以促进未来生物医疗、人工智能等领域的发展。本文介绍了国内外基于3D打印技术制造柔性传感器的最新进展,其中包括聚酰亚胺等多种基底材料、纳米金属等多种打印传感材料;按照熔融沉积、黏弹性墨水沉积、粉末烧结熔化、还原光聚合和材料喷射的制造原理分别阐述了多种传感器的材料选择、成型特点,并对制造方法进行总结分析。虽然3D打印制造柔性传感器件存在着缺乏行业标准及多种类打印材料等问题,但经过不断创新与发展,3D打印将成为柔性传感领域极佳的制造手段。     

Construction of Micro-Patterned Polymer Structures by Piezoelectric Inkjet Printing

It is not simple to accurately deposit minute quantities of polymeric materials by inkjet printing systems. High viscosity, nozzle clogging, agglomeration, precipitation, and uncontrollable drying patterns are serious problems which are frequently encountered in polymer inkjet printing. In this study, we investigated how inkjet printability of polymers correlates with the polymer ink formulations and inkjet process variables. After a systematic study with different variables, various patterns such as dots, cross stripes, and honeycombs were fabricated on flexible polyimide (PI) films and the pattern morphology and spatial distribution of the resulting polymer deposits after solvent drying were characterized.     

Production of a stable and homogeneous colloid dispersion of nano CoAl2O4 pigment for ceramic ink-jet ink

Different types of nano-CoAl₂O₄ pigments were prepared by controlling concentration of cetyltrimethylammonium bromide (CTAB) and polyvinyl pyrrolidone (PVP) as double capping agents in a co-precipitation process. The prepared nano-CoAl₂O₄ pigments were characterized by TGA, UV spectroscopy, and XRD. The optimum synthesized nano pigment was well dispersed into de-ionized water to form the ink. Rheology, surface tension and DLS of the prepared ink were examined. The prepared ink was printed onto a ceramic substrate. The printing process was repeated 1, 3 and 5 times in order to evaluate variations in the optical properties by changing thicknesses of the printed film. Appearance of the printed image and morphology of the prepared nano-pigments were observed by SEM. Moreover, shape and size of the nano-particles in the prepared ink were investigated by TEM. The obtained results revealed that the ink-jet printing method can be used to produce a nano-film of pigments on the ceramic.     

印刷油墨清洗剂的技术现状及发展趋势

对印刷油墨清洗剂的国内外研究进展进行了综述,概括分析了传统汽油、煤油类油墨清洗剂,混合溶剂型,乳化、微乳型,水基、半水基型,植物油基型等新型油墨清洗剂的优点与缺陷,并对油墨清洗剂的发展趋势进行了展望。     

喷墨技术进展及在电子元件中的应用

喷墨印刷可称之为当前发展最快的印刷技术。为了提高喷墨印刷的质量和扩大喷墨印刷的适用范围,人们正在进行大量的研究和开发工作。本文概要介绍喷墨技术的特点及原理;阐述了喷墨墨滴的产生方法、喷墨油墨以及喷墨介质的性能要求;同时指出了喷墨技术的新进展及其在电子元件中的应用。     

Gravure printing for thin film ceramics manufacturing from nanoparticles

Printing technologies can offer high potential for the thin film deposition of functional materials. Among the printing techniques, the gravure is considered one of the most promising, although to date it is still little employed, especially for the inorganic functional materials. In this work, the study of the gravure printing process for the metal oxides thin film production on flexible polymer substrate is reported. For this purpose, zinc oxide (ZnO) was chosen due to its versatile properties and nanosize effects, which make it suitable for many high technology areas. The gravure printing was made using low viscosity inks of ZnO nanoparticles. The characteristics of the printed thin films were examined and discussed. Thanks to the understanding of the physics underlying the film forming during the printing process combined to the knowledge on such specific material, uniform, compact, very transparent and smooth films were obtained in different nanometric thicknesses. Moreover, the possibility of fabricating ceramic nanocomposite films directly through this printing technique is also presented. Thanks to its scientific approach, this work makes available to the world of ceramics an industrial versatile and low-cost production technique which can allow to study and develop high-quality thin film ceramics with technologically interesting properties as well as nanoparticles behavior and their treatments in order to develop and use their fascinating nanosize properties.     

Printed thermochromic displays

Thermochromic displays, which were evaluated in this study, combine printed electronics with the thermochromism phenomenon. Conductive lines printed on the reverse side and thermochromic printing ink printed on the front side of cardboard packaging form a thermochromic display that gives cardboard packaging additional value. Displays were printed on different printing materials, and thermochromic printing ink was deposited in one and two layers. In addition, half of the samples were varnished. The influence of the printing material, the thickness of the thermochromic printing ink layer, the varnish, the high temperature, and light fastness on the display's operability were all evaluated. It was clearly shown that the choice of printing material plays a crucial role in the display's operability. Moreover, high temperature and light fastness also have a significant influence, although the impact is negligible when the display is used at room temperature.     

A comparative study on roll-to-roll gravure printing on PET and BOPP webs with aqueous ink

Ink transfer and printing characteristics in high-speed gravure printing were investigated on poly(ethylene terephthalate) (PET) and biaxial-oriented polypropylene (BOPP) substrates employing a pilot-scale gravure printing machine (maximum speed: 500 m min⁻¹). The flexible substrates were printed in an aqueous ink diluted with ethanol under various machine factors such as printing speed, nip force, and groove size.     

Impact of ink formulation on carbon nanotube network organization within inkjet printed conductive films

The inkjet printing of an aqueous suspension of carboxylic acid-functionalized single walled carbon nanotubes (SWCNT-COOH) and of a conductive ink combining SWCNT-COOH with the conductive polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid) (PEDOT-PSS) was studied. A dimensionless study predicted the behavior of these two fluids in a given printing system. Observations at different scales were performed on the printed samples to visualize the arrangement of the carbon nanotube (CNT) network within the printed layer. An innovative way to localize CNTs within the printed patterns was developed by using a mapping technique of surface sample, based on a scanning electron microscope coupled with an energy dispersive X-ray spectroscope. The SWCNT-COOH aqueous suspension is subject to the halo (or “coffee ring”) effect, which is a well-known phenomenon in inkjet printing, whereas the SWCNT-COOH/PEDOT-PSS ink offers a more homogeneous CNT network. The CNT orientation has also been under investigation. For the SWCNT-COOH suspension, specific orientations of the CNTs were recorded, whereas for the SWCNT-COOH/PEDOT-PSS ink, a more homogeneous CNT distribution with a random orientation was obtained. This study proved also that the droplet ejection velocity can have an impact on the CNT distribution and consequently on the electrical performances of the ink.     

Suture Fiber Reinforcement of a 3D Printed Gelatin Scaffold for Its Potential Application in Soft Tissue Engineering

Gelatin has excellent biological properties, but its poor physical properties are a major obstacle to its use as a biomaterial ink. These disadvantages not only worsen the printability of gelatin biomaterial ink, but also reduce the dimensional stability of its 3D scaffolds and limit its application in the tissue engineering field. Herein, biodegradable suture fibers were added into a gelatin biomaterial ink to improve the printability, mechanical strength, and dimensional stability of the 3D printed scaffolds. The suture fiber reinforced gelatin 3D scaffolds were fabricated using the thermo-responsive properties of gelatin under optimized 3D printing conditions (−10 °C cryogenic plate, 40–80 kPa pneumatic pressure, and 9 mm/s printing speed), and were crosslinked using EDC/NHS to maintain their 3D structures. Scanning electron microscopy images revealed that the morphologies of the 3D printed scaffolds maintained their 3D structure after crosslinking. The addition of 0.5% (w/v) of suture fibers increased the printing accuracy of the 3D printed scaffolds to 97%. The suture fibers also increased the mechanical strength of the 3D printed scaffolds by up to 6-fold, and the degradation rate could be controlled by the suture fiber content. In in vitro cell studies, DNA assay results showed that human dermal fibroblasts’ proliferation rate of a 3D printed scaffold containing 0.5% suture fiber was 10% higher than that of a 3D printed scaffold without suture fibers after 14 days of culture. Interestingly, the supplement of suture fibers into gelatin biomaterial ink was able to minimize the cell-mediated contraction of the cell cultured 3D scaffolds over the cell culture period. These results show that advanced biomaterial inks can be developed by supplementing biodegradable fibers to improve the poor physical properties of natural polymer-based biomaterial inks.     

喷墨打印技术的发展现状

简要介绍了喷墨打印技术的发展现状。目前主要有两类喷墨打印技术:连续喷墨打印和脉冲喷墨打印技术。前者可设计成双重或多重弯曲系统;后者可分为热喷墨、压电喷墨、阀门喷墨、静电喷墨过程,描述了喷墨打印用墨的最新发展。水性、溶剂性、热熔性、紫外固化和反应性墨是目前主要的喷墨打印用墨。     

Color reproduction of authenticable luminescent backlit transmissive color images

We propose a method for creating authenticable color images under UV excitation backlight by printing an invisible luminescent white emissive ink layer on the verso side of a transmissive substrate and a classical cmy image on the recto side of the substrate. In order to obtain a backlit image whose colors are as close as possible to the original image colors, we map the input image sRGB color gamut into the gamut formed by the emissive white source attenuated by the classical ink halftones. The relationship between surface coverages of the classical cmy ink halftones and the resulting backlit colors is obtained by accounting for the transmission of the emissive white through the paper substrate and through the classical cmy ink halftones. The transmittance of the classical ink halftones is modeled by a new halftone absorbance prediction model. The lightness range of the luminescent backlit color gamut is expanded by printing a black and white UV‐absorbing instance of the original color image in superposition with the luminescent white emissive layer and in registration with the cmy image printed on the recto side. Luminescent backlit color images provide a high anticounterfeiting security, as they combine a verso printed invisible luminescent ink layer, a verso printed black and white instance of the original image and a matching recto printed cmy instance of the original image. The resulting luminescent backlit image colors are close to the original image colors only when observed in transmission mode under UV light. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 331–340, 2014